Method for producing petroleum



Xi? 333E9 July 25, 1967 w. A. COLBURN METHOD FOR PRODUCING PETROLEUM Filed Nov. 13. 1964- u-mim sai wxm aimi iHV Faas INVENTOR.

William A. Colburn ATTORNEYS United States 3,332,485- METHOD FOR PRODUCING PETROLEUM, William A. Colburn, 3719 S. Glencoe St,

Denver, Colo. 80222 Filed Nov. 13, 1964, Ser. No. 410,998 16 Claims. (Cl. 166-9) This invention relates to the recovery of petroleum from geologic fonnations and particularly an improved method for utilizingwater flooding in the production of.

- petroleum.

Various methods have been employed in the petroleum industry for the recovery of petroleum from-geologic formations. For example, in primary recovery methods wells are drilled intothe petroleum reservoir formation in a pattern or spacing which is based primarily on geographic locations. As oil is produced from these wells the pressure of the oil drops and the production from such wells decreases and becomes increasingly dificult. Subsequently, secondary recovery or repressurizing techniques may be employed to return the producing wells In conventional pattern flooding each producing well is surrounded by a number of injection wells which are intended to force the oil toward the producing well, and

little or no consideration .is given to structural characteristics in the secondary recovery methods conventionally employed at the present time.

The present invention is based upon-the discovery of a direct relationship between the direction of water flow with respect to the direction of structural clip on one hand and the oil-water production ratio of the well on the other. Accordingly, it is an object of this invention to provide an improved petroleum recovery method utilizing this relationship to increase the recovery of petroleum from geologic formations.

It is another object of this invention to provide a meth-.

od for improving the efiiciency of producing wells and including a method for maintaining a high capillary pressure at the producing wells.

It is another object of this invention to provide a atent The features of novelty which characterize this invention are pointed out with particularity in the claims annexed to and forming a part of-this specification.,l'he

method for improving the efliciency of water injection wells employed in the recovery of petroleum.

It is another object of this invention to provide an improved recovery method for maintaining the pressure in a producing formation substantially the same as that of the original field pressure.

Briefly, in carrying out the objects of this invention in. the practice of one method thereof, a relationship of injection and production wells is provided in a petroleum field in such manner that the direction of water flow from the injection wells toward the production wells is predominantly updip in the immediate zone of the production wells. In a further embodiment of the invention l the production in a petroleum field is moved progressively over the field keeping the water flow in a predominantly updip direction in the immediate zone of the production wells, new wells being utilized for production and former production wells for injection while the former injection wells are abandoned at least temporarily.

method of the invention itself, however, together with further objects andadvantages thereof, mayv best be understood upon reference to the following description taken in connection with the accompanying drawings in which:

FIG. 1 is a diagrammatic illustration of a petroleum field provided with wells drilled in a pattern in accordance with conventional practice and illustrating the application of the method of this invention to such field;

FIG. 2 is a diagrammatic sectional view through a plurality of the wells of the field of FIG. 1 talren along a I the line 22 thereof; and

FIG. 3 is a diagrammatic illustration of the same field 7' as that of FIG. 1 but with the wells drilled at locations selected in accordance with a procedure employing the present invention.

Referring now to the drawings, the ing field illustrated in FIG. 1 comprises an area 10 sloping from the top to the bottom as indicated by. successive structure contour lines 11, 12, 13 and-14, the line. 11

being the highest in elevation. The field has been drilled in the conventional grid pattern on a geographical basis,

each well, for example,

being drilled in the center of a 40-acre square.

When the wells drilled in a field such .as here repre- Patented July 25, 1967' petroleum producsented decrease in production until some method of secondary recovery must be sought, it is conventionalpractice to employ water flooding- In accordance with this practice half of the wells are converted from producing,

wells to injection wells. For example, in the conventional five-spot water flooding pattern all the wells along a se-' lected diagonal are converted to water injection wells,

the wells along adjacent diagonals remaining as production wells and the diagonals throughout the field being alternately injection and producing well diagonals. 1

For example, in FIG. 1 the wells along the diagonals indicated by dotted lines 15, 16 and 17 remain as producing wells and the wells in the intermediate diagonals are converted to be water injection wells. It will now be seen that this provides a series of five-spot patterns. For example, the well 18 in line 16 remainsa production well and the surrounding four wells designated 20, 21,

22 and 23 are converted to injection wells. Thus water the formation and facilitate the production of oil from the well 18. This pattern is continuous throughout the Y field, each production well having four injection wells near it located in the same relationship as the injection.

wells 10-43 are to the production well 18.

The water forced into the formation through the injec-- tion wells in this conventional procedure not only tends to force oil toward well 18 but also causes a downdip flow of water toward the lower zonesof the formation. Itwill be noted that the flow of water toward the production wells 18 and 31 from injection well 23 is generally horizontal as indicated bythe contour lines and that flow to the production well 18 from injection well 20 is downdip whereas the flow tothe productionwell 18 from injection well 22 is updip. 1

In one embodiment of the present invention, when 'it is desired to effect water flooding in a field such as the field 10, injection wells are so located that the flow-in inantly updip. For this purpose, assuming the wells in the top row are to remain in production, then water isinjected for water flooding through the wells inthe next lower row and the wells in the third row are temporarily abandoned. The wells in the fourth row are used as proinjected into these four wells is intendedto pressurize the immediate zone of the production wells is predomduction wells and water injection is appliedto the-wells I in the fifth row while the wells in the sixth row are temporarily abandoned and the wells in the seventh row employed for production with water injection-in the eighth I'QW.

With this arrangement of water flood, there results a predominantly updip flow of water in the immediate zone of production wells as illustrated, by way of example, in FIG. 2 which is a sectional view taken through the left-hand row of wells as indicated by the section line,

. the first, fourth and seventh wells being producing wells as indicated at 25, 26 and 27, and the second, fifth and eighth wells being water injection wells as indicated at 30, 31' and 32. The wells immediately below the injection wells are temporarily abandoned and injection proceeds.

As shown in FIG. 2, the well 25 enters a portion of the formation wherein a rich oil-to-water mixture is present as indicated at 33 and-water is injected throughthe well 30 and fills a zone generally designated at 34 providing updip pressure against the width of the zone toward the production well, whereupon production of high ratio oil-to-water fluids results;

The well indicated at 35 is maintained out of use while the next lower well 26 is a production well entering a high oil-to-Water ratio zone 36 similar to the zone 33, and injection through the well 31 forms a pressure front against the formation toward the well 26 while the intermediate well indicated at 37 is temporarily abandwells 25, 26 and 27 are discontinued, the injection wells 30, 31 and-32 are closed, and the intermediate walls 35 and 37, for example, are again used for production and the former production wells 26 and 27 are used for water injection, it being assumed in this case that the well 25 is at the topmost position in the formation and is therefore not used as an injection well. This second step and further injection results in the production of relatively high oil-to-water fluids through the wells 35 and 37 and further production is secured from the formation.

' The water flooding of a field in the manner just described effects a production of high oil-water ratio fluids and maintains high capillary pressure at the producing wells and low capillary pressure at the injection wells, It will be understood that the injection through the wells 30 and 31 as indicated in FIG. 2 does result in downflow of water into the portions of the zones below the wells 35 and 37. However, since the distance to the lower wells 26 and 27 is greater than to the wells 25 and 26, respectively, by temporarily discontinuing operation of the wells 35 and'37 the production of low oil-to-water ratio fluids is prevented and the injection is continued until such time as the wells 25, 26 and 27 produce lower oil-to-water ratio fluids.

When a field is to be drilled for initial production to fully utilize the advantages of the present invention, this may be accomplished in the-manner indicated in FIG. 3. Here a field 40 of the same geological configuration as the field has been shown as drilled with rows of wells falling generally along contour lines instead of in the geometrical grid pattern. In this figure the same contour lines as those indicated in FIG. 1 have been designated by the same numerals with the suffix letter a. The spacing between the lines of wells and the spacing between wells in a line are, of course, determined by location regulations and also by the characteristics of the geologic formation and by the characteristics of the reservoir fluids. In carrying out the method of the present invention it is only necessary that the wells to be used 4- as injection wells be positioned so that the flow will be predominantly updip in the immediate zones of the production wells.

In developing a field such as this, pairs of rows are drilled with spaces between pairs for rows of additional wells to be drilled. As shown in FIG. 3, three pairs of rows of wells have been drilled comprising rows 42 and.

43, rows 44 and 45, and rows 46 and 47, each pair of rows being separated by a distance ,sufiicient for drilling a future row of wells indicated between the first and second pairs at 48, between the second and third pairs at 49, and below the third pair at 50. Water is then injected into the wells in rows 43, 45 and 47 which are the downdip rows of each pair of rows, and oil is produced from the wells in rows 42, 44 and 46.

When the wells in the upper rows 42, 44 and 46 begin to produce low oil-to-water ratio fluids, their production is discontinued and wells are drilled in the rows indicated at 48, 49 and 50. These new wells are then employed as production wells and water is injected into the wells in rows 44 and 46. The former injection wells 43, 45 and 47 are closed or abandoned, and to facilitate the production of fluid from the wells in the row 50 a lower row of wells indicated at 52 is drilled and employed for the injection of water. When the wells in these new production rows 48, 49 and 50 begin to produce low oil-to-water ratio fluids, production in the field has been completed and is terminated.

When a field is produced by employing this arrangement, producing wells will produce high oil-water ratios and less water will be needed for injection. Furthermore, lower injection pressures can be used and thus smaller separator tanks will be required and smaller water treatment plants needed. I

- While this invention has been described in connection with the application of the method to specific drilling patterns or arrangements, various modifications and applications to other geological formations will occur to those skilled in the art. Therefore it is not desired that the invention be limited to the details and formation configurations illustrated and described and it is intended by the appended claims to cover all modifications which fall within the spirit and scope of this invention.

I claim: 1. The method of producing petroleum from a geologic formation wherein a plurality of wells have been drilled which comprises injecting water into one of the wells lying downdip from at least one other of the wells, and said injection well lying updip from the lowermost edge of the petroleum accumulation, and producing petroleum from second wells updip from said injection well whereby the flow of water from said injection well is predominantly updip and the capillary pressure is high in the immediate zone of said second wells and the oil-towater production ratio is high from said second wells and the capillary pressure is low in the immeditae zone of the injection well.

2. The method of producing petroleum as set forth in claim 1 including the step-of temporarily discontinuing production from third wells which lie immediately downdip from said injection well.

3. The method of producing petroleum as set forth in claim 2 including the steps of injecting water into a fourth well lying sufiiciently far updip from said second wells so that said second wells shall remain under updip water flow conditions, and producing petroleum from fifth wells updip from said fourth injection well.

4. The method of producing petroleum as set forth in claim 3 including the step of temporarily abandoning pro duction from sixth wells lying updip from said second wells and downdip from said fourth wells.

5. The method of producing petroleum from a partially depleted petroleum field having a plurality of wells drilled thereinto which compiises injecting water into selected ones of the wells which lie updip from the lowermost edge.

from second selected ones of said wells each lying updip from the nearest one of said injection wells whereby the flow of water from said injection wells toward said second wells is predominantly updip and the capillary pressure is high in the immediate zone of said second wells and the oil-to-water production ratio is high from saidsecond wells and the capillary pressure in the immediate zone of said injection wells is low.

6. The method of producing petroleum as set forth in claim 5 including the step of temporarily discontinuing production from third wells which lie immediately downdip from said injection wells. 7

7. The method for effecting more complete recovery of I petroleum from'a geologic formation having a plurality of wells therein which comprises injecting water into a selected first well downdip from an adjacent second well and updip from the lowermost edge of the petroleum accumulation, and producing petroleum from said second well so that the flow of water from said first well to said second well' is predominantly updip and the capillary pressure is high in the immediate zone of said second well and the oil-to-water ratio from the second well is high and the pressure in the formation is substantially maintained and the capillary pressure in the immediate zone of said first well is low.

8. The'method of recovery of petroleum as set forth in claim 7 including the step of temporarily discontinuing production from third wells which lie immediately downdip from said first well.

9. The method for effecting more complete recovery of petroleum from a geologic formation having a plurality of wells therein which comprises injecting water into afirst plurality of the 'wells which are updip from the lowermost edge of the petroleum accumulation, selecting a second plurality of wells lying updip from said first plurality, and producing petroleum from said second plurality of wells whereby the flow of water from said first plurality of wells toward said second plurality is predominantly updip and the capillary pressure is high in the immediate zone of said second plurality of wells and the oil-to-water production ratio is high from said second plurality of wells and the capillary pressure in the immediate 4 zone of said first plurality of wells is low.

10. The method of recovery of petroleum as set forth in claim 9 including the step of temporarily discontinuing production from a third plurality of wells which lie immediately downdip from said first plurality of wells.

11. The method for effecting efficient recovery of petroleum from a geologic formation which comprises providing first and second wells extending into the formation,

6 second well and the capillary pressure in the immediate zone of said first well is low.-

12. The method of recovery as set forth in claim 11 f including the steps of providing third and fourth wells. the

third well being driven to a zone sufficiently updip from the second well so that the second well will remain under predominantly updip water flow conditions, and said fourth well drilled updip from said third WelLinjecting water into said third well, and producing petroleum from said fourth well whereby the ilow of water from said third well towardsaid fourth wellis predominantly updip andthe capillary pressure is high in the immediate zone of said v. fourth well and the capillary pressure in the immediate zone of said third well will be low.

13. The method of producing petroleum from a geo- .logic formation wherein a plurality of wells have been drilled which comprises selecting a first row of wells above the lowermost part of the petroleum accumulation which lie approximately on a structure-contour line as injection wells, selecting at'least one row of second wells spaced updip from'said first wells as producing wells whereby a predominantly updip flow of water from said first wells and high capillary pressure will be maintained at said second wells and a high oil-to-water production ratio will be obtained from said second wells and the capillary pressure '7 in the immediate zone of said first wells will be low.

14. The method of producing petroleum as set forth i in claim 13 including a step of selecting arm of third wells spaced downdip from the row of injection wells as Y wells to be kept inactive temporarily.

15. The method of producing petroleum as set forth in claim 14 including the steps oil-repeating the pattern of rows of wells in the remainder of the field.

16. The method for effecting efiicient recovery of pe troleum from a geologic formation which comprises providing a first row of water-injection wells lying above the lowermost part of the petroleum accumulation and extending into the formation approximately along a structure-oontour line and providing at least one row of second wells as producing wells spaced undip from said first wells, and providing at least one row of third wells downdip from said first wells to be maintained temporarily inactive whereby a predominantly updip fiow of water from said I first wells and high capillary pressure will be maintained at said second wells and the oil-to-water production ratio is high from said second wells and a low capillary pressure will be maintained at said first wells.

References Cited UNITED STATES PATENTS 1,885,807 11/1932 Doherty l66-9X v 2,630,182 *3/1953 Klotz 166-9 3,251,412 5/1966 Cooke etal "166-9 Y CHARLES E. OCONNELL, Primary Examiner.

STEPHEN I. NOVOSAD, Examiner.

Atkinson. 166--9 

1. THE METHOD OF PRODUCING PETROLEUM FROM A GEOLOGIC FORMATION WHEREIN A PLURALITY OF WELLS HAVE BEEN DRILLED WHICH COMPRISES INJECTING WATER INTO ONE OF THE WELLS LYING DOWNDIP FROM AT LEAST ONE OTHER OF THE WELLS, AND SAID INJECTION WELL LYING UPDIP FROM THE LOWERMOST EDGE OF THE PETROLEUM ACCUMULATION, AND PRODUCING PETROLEUM FROM SECOND WELLS UPDIP FROM SAID INJECTION WELL WHEREBY THE FOLW OF WATER FROM SAID INJECTION WELL IS PREDOMINANTLY UPDIP AND THE CAPILLARY PRESSURE IS HIGH IN THE IMMEDIATE ZONE OF SAID SECOND WELLS AND THE OIL-TO-WATER PRODUCTION RATIO IS HIGH FROM SAID SECOND WELLS AND THE CAPILLARY PRESSURE IS LOW IN THE IMMEDITAE ZONE OF THE INJECTION WELL. 